Production of cyclic ketones



ateiated Get. 9, 1945 2,386,372 monoc'rrou or creme arrears- 1 Gary R. Wagner, Utica, Petroleum Company, a

Ohio, assignor to Phillips corporation of Delaware No Drawing. Application April 20, 1944, Serial No. 531,995

5 Claims.

to the oxidation of all- More specifically, it pertains to the catalytic vapor phase oxidation of cycloparafiins'having from five to six carbon atoms in the ring, namely, cyclopentane, cyclohexane, and their respective alkyl derivatives, especially methylcyclopentane and methylcyclo- This invention relates cyclic hydrocarbons.

hexane, to form the corresponding cyclic ketones.

The production of alicyclic ketones by the oxidation of alicyclic hydrocarbons hasbeen accomplished heretofore. Donald J. Loder, discloses a process in which cyclohexane is oxidized in the liquid phase at temperatures of from 100 C. to 250 C. by means of an oxygen-containing g s in the presence of cobalt naphthenate catalyst. The products comprise a mixture of cyclohexanol and cyclohexanone. Similarly, U. S. Patent 2,285,914 to Dressbach, discloses obtaining a 4 per cent yield of cyclohexanone from cyclohexane by liquid. phase oxidation. 3

By the process of my invention the oxidation of a cycloparafiin of carried out in the vapor phase, thereby avoiding the high pressures necessary when operating in the liquid phase and giving rise to many advantages.

The oxidizing gases employed in my .process may be air or other Under certain conditions of operation, as when an especially active oxidation catalyst is being used, it may be advantageous to limit the percentage of oxygen in the oxidizing gas mix- 35 ture to a value below that of ordinary air, say to 5 to 10 per cent by volume. In this way the production of higher oxidation products may be held to a minimum.

' In carrying out my process, I pass a preheated i mixture of the cycloparaflln vapors and oxygencontaining gas over an oxidation catalyst at a temperature in the range of 300 to 550 C. The flow rate of this gaseous mixture is adjusted so as to result in a contact time of from 0.1 to 10 45 seconds, depending upon the activity of the catalyst, the temperature, and the oxygen content of the mixture. It is preferred to operate at relatively short contact .times, recycling any unchanged hydrocarbons and intermediate oxida- 0 tion products which may be found in the reactioneiiluent. In this way'the production of higher oxidation products may be minimized and ultimate yields increased;

Catalysts which may be employed in my proc- U. S. Patent 2,223,494-150 ess include the following metals or other oxides, or mixtures thereof: silver, copper, vanadium, chromium, manganese, iron, cobalt, nickel, platinum, and palladium. These may be employed in the form' of screen or gauze, or may be supported on inert carriers such as asbestos. Silver oxide is the preferred catalyst.

As an aid in controlling the reaction tempera.- ture, steam may be introduced either with the oxygen-containing gas or separately into the catalyst zone.

It has been found that by the use of the above I specified conditions the reaction which is otherfrom five to six carbon atoms in the ring to form the corresponding ali cyclic ketone is wise very difflcult to control so as to avoid obtaining large amounts of higher oxidation products than the desired alicyclic ketones, the oxidation of the present invention is very easily kept under control and gives very good yields of the cyclic ketones.

' Following is a specific non-limiting example of the practice or the present invention:

Example Methylcyclohexane vapors and air, in the ratio 1:5 by volume, were preheated to 300 C. and passed over a silver oxide catalyst maintained at a temperature of 400-450" C. The catalyst was supported on asbestos and was contained in a copper tube 5 mm. in diameter and 20 cm. in

oxygen-containing gases of W length. Contact time was 0.3 second. The eliiu- -about the same oxygen content as that of air.

- ing from five to six carbon atoms in the ring to Y the corresponding cyclic passing a vaporous feed consisting of said cycloclohexane vapor and air in the ratio eyclohexane and air over ketone which comprises paramn and air over an oxidation catalyst consisting of silver oxide at a temperature of from cyclic ketone from the resulting efiluent.

2. The method of oxidizing methylcyclohexone to methylcyclohexanone which comprises passing a vapcrous feed consisting of methylan oxidation catalyst consisting of silver oxide at a temperature of from 300 to 550 C. and for a contact time of from 0.1 to 10 seconds, and recovering methylcyclchexanone from the resulting effiuent.

I 3. The method of oxidizing methylcyclohexane to methylcyclohexanone which comprises passing a vaporous mixture consisting of methylcyof 1:5 by

consisted largely of the.

0., and recovering the corresponding 1 catalyst consisting of silver oxide at a pressure such as to maintain vapor phase and at a temperature of from 300 to 550 C. and for a contact time of from 0.1 to 10 seconds, and recovering said corresponding cyclic ketone from the resulting emuent.

5. The method of oxidizing cycloparaflins having from five to six carbon atoms in the ring to the corresponding cyclic ketone which comprises passing a vaporous mixture of said cycloparaflin and a. gas containing from 5 to 10 per cent by volume of oxygen over an oxidation catalyst consisting of silver oxide at a pressure such as to maintain vapor phase and at a temperature of from 300 to 550 C. and for a contact time of from Oil to 10 seconds, and recovering said corresponding cyclic ketone from the resulting effluent.

CARY R. WAGNER. 

